The invention relates to a two-part piston for an internal combustion engine.
A two-part piston for an internal combustion engine, which consists of an upper part and a lower part, is known from the patent application having the file number DE 10 2005 021 427.4. The upper part forms the piston crown and has a cylindrical pin having an outside thread, which pin lies coaxial to the piston axis, on the underside facing away from the piston crown. The lower part has an upper, thin-walled, and elastically resilient crown part, at the central region of which a sleeve pointing in the direction of the piston crown is formed on, having walls that are so thin that this sleeve has the function of an expansion sleeve. An opening that lies coaxial to the piston axis is formed into this expansion sleeve, into which opening the pin is introduced, so that the upper part can be connected with the lower part by means of a nut screwed onto the pin, whereby the elastic resilience of the upper crown part and the expandability of the expansion sleeve puts the screw connection under bias, and thereby imparts great reliability to the latter.
It is disadvantageous that the production of the upper crown part of the lower part, with the expansion sleeve formed on, is very complicated. In this connection, time-consuming machining of the central region of the upper crown part and, in particular, of the expansion sleeve, is required, independent of whether the lower part is cast or forged, whereby attention must be paid to the adherence of close tolerances, so that the central region of the upper crown part and the expansion sleeve adhere to the desired elasticity properties.